I just recently purchased my bimmer E39 and Im getting a rattling/vibration noise only when I accelerate and between 1 - 2000 rpms. never when idling or reverse. the car rides and drives smooth no shuttering and that noise only happens at those specific rpms at slow speed. my guess is loose heat shield? any ideas? im used to working on american and asian but im finding bmw is a whole other type of machine. I also have a small ATF leak from either where you fill it or one of the hoses what fluid would any of you recomend. and finally what type of oil do you fellow bimmer owners find works better and prefer in yours? Any advice is welcome and thanks.

sounds like a heat shield or a cat